Zika infection linked to Guillain-Barre syndrome in South America

Scientists at Johns Hopkins School of Medicine in Baltimore, MD, and at 6 hospitals in Colombia, South America, reported results that support the role of Zika virus infection in the development of at least some cases of Guillain-Barré syndrome. This is the strongest biological evidence yet to link Zika infection with Guillain-Barré, according to their October 5, 2016 study in The New England Journal of Medicine.

Starting in December 2015 and into the early months of 2016, during the height of the Zika outbreak in Colombia, an unusually high number of Guillain-Barré cases were reported—270 suspected cases in the first 12 weeks of 2016.

“At the beginning of the Zika outbreak in South America, my colleagues in Colombia contacted me with concern about the increasing number of patients with neurological complications in their hospitals,” said corresponding author Carlos A. Pardo, MD, Associate Professor of Neurology and Pathology at Johns Hopkins.

To investigate the relationship between these diseases, the researchers evaluated a total of 68 patients in Colombia who were diagnosed with Guillain-Barré syndrome from January 2016 to March 2016. In most cases, the diagnosis of Guillain-Barré syndrome was confirmed by nerve-conduction studies and electromyography.

The researchers obtained blood, cerebrospinal fluid, and (when available) urine samples from these patients for virologic testing. Of the 68 patients, 42 underwent Zika virus testing by reverse-transcriptase PCR assay in at least 1 of the 3 biologic samples.

Of those 42 patients, 17 (40%) tested positive for Zika virus. (Notably, 16 of these 17 patients were diagnosed based on urine samples.) Almost all patients had 2 or more clinical symptoms of Zika infection, which include fever, headache, rash, and conjunctivitis.

None of the patients tested positive for dengue virus.

Twenty of these 42 patients had a rapid onset of neurologic symptoms that occurred within 4 days of Zika virus infection—an unusually fast response, the researchers noted. Neurologic symptoms included limb weakness, ascending paralysis, paresthesias, and facial palsy. The researchers determined that the majority of patients had the acute inflammatory demyelinating polyneuropathy (AIDP) subtype of the syndrome.

The results of this study support that Zika virus is involved in these cases of Guillain-Barré syndrome, the researchers concluded.

However, Dr. Pardo acknowledged, the study doesn’t reveal what biological mechanisms may allow Zika to initiate an immune attack on the nerves.